A METASTABLE STATE OF POSITRONIC HELIUM

A metastable state of helium with an attached positron is predicted to exist with a total energy of -2.2505916 Hartree. The state is stable against dissociation into He+ + Ps with a binding energy of -0.0005916 Hartree. This state is formed by the attachment of a positron to the metastable He 1s2s S-3(c) state. The He (S-3(e))e(+) S-2(e) state has a 2 gamma decay rate of 5.67 x 10(9) s(-1). The He(S-3(e))e(+) S-4(e) state can only decay by a 3 gamma process with an approximate rate of 7.1 x 10(6) s(-1). The structure of these states are best characterize d as a positronium atom orbiting a He+ 1s core at large distances.